| (19) |
 |
|
(11) |
EP 0 484 168 A3 |
| (12) |
EUROPEAN PATENT APPLICATION |
| (88) |
Date of publication A3: |
|
11.08.1993 Bulletin 1993/32 |
| (43) |
Date of publication A2: |
|
06.05.1992 Bulletin 1992/19 |
| (22) |
Date of filing: 31.10.1991 |
|
|
| (84) |
Designated Contracting States: |
|
DE FR GB |
| (30) |
Priority: |
31.10.1990 JP 292117/90
|
| (71) |
Applicant: NGK SPARK PLUG CO., LTD |
|
Nagoya-shi (JP) |
|
| (72) |
Inventors: |
|
- Oshima, Takafumi
Nagoya-shi (JP)
- Ogura, Hiroyasu
Nagoya-shi (JP)
|
| (74) |
Representative: Cresswell, Thomas Anthony et al |
|
J.A. KEMP & CO.
14 South Square
Gray's Inn
London WC1R 5LX
London WC1R 5LX (GB) |
|
| |
|
| (54) |
A glass sealant of spark plug insulator for use in an internal combustion engine |
(57) In a spark plug insulator, an electrically conductive sealant in provided to connect
a center electrode to a terminal electrode which are provided within an axial bore
of the tubular insulator. The glass sealant is made from the following materials:
(a) granular aluminosilicate glass consisting of silica (SiO₂), alumina (Al₂O₃), alkali
metal oxides and alkali earth metal oxides, granular size of the aluminosilicate glass
being more than 250 µ; (b) granular silicate glass, granular size of which is less
than 74 µ; and (c) powdered metal, granular size of which is less than 74 µ, and selected
from the group of nickel, chromium and nickel-chromium alloy.